Abscess Of Lung With Pneumonia

History

Fact

Explanation

A diagnosed patient with pneumonia

Lung abscess is usually suspected when a diagnosed patient with lower respiratory tract infection fails to respond to the conventional and, assumed as adequate antibiotics. [1] The commonest causative organisms for lung abscesses are the anaerobic bacteria (in cases of aspiration pneumonia), aerobic bacteria (rare but in cases of community aqcuired pneumonia), and Mycobacterium. [2] [3] A lung abscess develops when a bacterial infection causes necrosis and produces cavities in the lung parenchyma. [4]

A risk factor for developing pneumonia and lung abscess

The commonest risk factors for aspiration pneumonia are are alcoholism related stupor, neurological disability, advanced age and lung malignancies. Once pneumonia is there, the predisposing factors for development of a lung abscess are immunosuppression, steroid therapy, carcinoma at a distant site, alcoholism, and lung cancer. [5] [6] [7] It's more common in males than females. [7]

Fever

Some patients present with fever of unknown origin [1] and some patients present with high fever with chills. [4] Fever is one of the commonest symptoms in lung abscess. [8]

Cough with sputum production

Productive cough with variable sputum is one of the commonest features in lung abscess. The sputum may be colored, depending on the infected organism, and foul-smelling. [4] [7] [9] There can be tinges of blood also. [10]

Chest pain

Chest pain of pleuritic nature is a common feature in lung abscess and pneumonia. [4] [11] But chest pain should be evaluated since it can be a feature of other complications as well. [12]

Examination

Fact

Explanation

Fever

Because of necro-inflammation in the lung parenchyma. IT could be a low grade nocturnal fever in cases of chronic lung abscesses, or high fever with chills in acute lung abscess and bacterial pneumonia. It's one of the commonest presentations. [1] [2] [3]

Digital clubbing

Nail clubbing develops sub-acutely in chronic suppurative conditions like lung abscess and empyema. [4] [5] [6] It should be evaluated according to the stage of clubbing. [4]

Cyanosis

Since there is an inflammation of the lung tissue which is important in gas exchange, there is going to be an oxygen un-saturation of blood, evident as bluish discolouration of tongue, mucus membranes (central cyanosis) and nail beds (peripheral cyanosis) . [7] [8]

Poor oral hygiene

One of the commonest risk factor for lung abscess following aspiration pneumonia. [9]

Tachypnea

Due to hypoxia and sympathetic stimulation. Taken alone, it has no diagnostic value in pneumonia. [10]

Features of respiratory distress

In severe pneumonia or the infection progressing to acute respiratory distress syndrome. [12] [13] Use of accessory muscles for breathing, tachypnea and tracheal tug are common findings.

Features of lung consolidation

The features of lung damage and consolidation might be obvious in respiratory system examination such as reduced lung expansion, reduced air entry, more pronounced vocal resonance and dull note for percussion. [14]

Investigations - for Diagnosis

To detect leucocytosis or leucopenia together with shifts of differential count. It can direct the diagnosis to the probable causative organism groups. [1] [2] [3]

Sputum for microbiological studies

Examination of sputum is important in identifying the causative micro-organism. In the cases where the patient is able to produce sputum, then properly labeled sputum in the specific container should be sent for microscopy. But when the patient is unable to do so, sputum induction should be performed. The required microbiological studies are Gram stain, culuture and antibiotic sensitivity. [4] [5] [6] [7] [8] [9] [10]

Sputum for acid-fast bacilli

If tuberculous abscess is suspected. But sputum may not be positive unless the abscess ruptures into an airway. [11]

Chest X-ray

The main radiological feature in plain erect chest X-ray is a cavity with an irregular inside layer and air-fluid level. Most of the time the cavities are round in shape, and there is a thick area of consoliation around the cavity. These cavitatory lesions are seen in other conditions as well, i.e. infected bulla, cavitary tumor, mycobacterial infection, pulmonary infarction, pulmonary sequestration, and vasculitis. [12] [13] [14] [15] [16]

Contranst-enhanced computed-tomography of chest

More reliable than an X-ray. Vascularity also can be viewed in cases where malignancy is suspected. [12] [16] [17] [18]

Investigations - Fitness for Management

Fact

Explanation

Hemoglobin level

The pre-operative hemoglobin count allows the surgeon to correct it with blood before any surgical procedure. Post-operative hemoglobin count is an important predictor in mortality. [1] [2] [3] [4] [5]

Platelet count

Both low and high platelet counts are associated with undesirable outcomes following a surgery. [6] [7] [8]

Management - General Measures

Fact

Explanation

Optimize co-morbid conditions

Presence of co-morbid conditions increases the morbidity and mortality in any medical condition. [1] In emergency setting, of-course there isn't much valuable time left for dwelling on prolonged history taking. [2] In cases where the elderly or immobilized patients aspirating frequently, and also in cases where lung abscess is secondary to another lung disease such as lung carcinoma, ensuring that the patient's quality of life is improved is important. [3] Medical and surgical palliative care should be discussed with different specialists, so sometimes a multi-disciplinary team is needed. Most important are chest physiotherapy, stenting the airways, analgesics and antipyretics. All these include de-briefing the patient and the family previous to them. [3] [4] [5] [6] [7] [8]

References

CLOUGH ROBERT A.. The Effect of Comorbid Illness on Mortality Outcomes in Cardiac Surgery. Arch Surg [online] 2002 April [viewed 15 June 2014] Available from: doi:10.1001/archsurg.137.4.428

Management - Specific Treatments

Prolonged (1-3 months) oral antibiotics are the commonest mode of management. [1] Oral clindamicin is the drug of choice. Metronidazole, moxifloxacin are also valuable. [1] [2] [3] [4] [5] [6] [7] [8] Even though it is so, medical treatment can be failed if the patient has poor prognostic factors, such as a large abscess cavity (> 6 cm), compromised immunity, neoplasm, advanced age, reduced level of consciousness, or infection with certain aerobic pathogens (Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus). [1]

Surgical drainage

Some almost 20% of the patients with lung abscesses require surgical or percutaneous drainage due to medical treatment failure at some point. [1] CT-guided drainage offers best option and highest success rate. Endoscopy, ultrasound also can be used. [1] [8] [9] [10] [11]

Open surgery

Indicated in cases where there is a malignancy predisposing the lung cavitation (or suspected of a malignancy) or there are multiple cavities. [12] [13]

References

SMIEJA M. Current indications for the use of clindamycin: A critical review Can J Infect Dis [online] 1998, 9(1):22-28 [viewed 14 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250868